The present invention relates to a water-in-oil emulsion based coating and its applications as an internal and external substitute for conventional fat-based coatings in frozen desserts. It further relates to a method of coating a frozen confectionery product, for example, an ice confectionery.
In a conventional fat-coated frozen confectionary product, for example an ice lolly, bar, morsel, cone, cup or cake, the fat may account for some 45-60% by weight of the coating. In ice confectionary products with conventional fat-based coatings, the fat gives some brittleness to the coating, the coating does not properly adhere to the ice confectionary core, and there is a poor release of flavor in the mouth. In the art, water-containing natural food compositions, such as fruit juice, cannot be covered with conventional fat-based coatings.
In U.S. Pat. No. 5,556,659 there is claimed a process for coating a frozen confectionary product in which the coating composition has reduced calories in that it is in the form of a water-in-oil emulsion, wherein the emulsion comprises 40 to 55% by weight water, 2 to 4% by weight of an emulsifier system comprising decaglycerine decaoleate, and less than about 3% by weight water-soluble compounds. This coating was designed to reduce calories while keeping the crispness/brittleness.
In JP 59,059,149 there is disclosed a reduced cost and reduced calorie composition for enrobing an ice confectionary based on a water-in-oil emulsion, in which the emulsifier system is a combination of polyglycerine condensed ricinoleic acid ester as the major emulsifier, and one of a glycerine fatty acid ester, a sorbitan fatty acid ester, or lecithin as a sub-emulsifier. In the emulsion, additives like color, flavor, and seasoning were combined to inexpensively make ice creams with different colors and flavors. Nothing is mentioned, however, about the physical properties of coating made by the emulsion. The enrobing composition has a high fat content.
Thus, it would be desirable to provide a coating composition which, in addition to having a substantially reduced fat content, also has a soft texture, good adhesion to ice cream or other ice confectionery, good flavor release, good storage and heat-shock resistance properties, and which can be processed in a conventional coating operation. The present invention satisfies this need.
The present invention relates to a coating composition for coating frozen dessert products in the form of a water-in-oil emulsion. The coating composition includes about 20 to 35% by weight fat phase; about 80 to 65% by weight water phase, wherein the water phase comprises about 10 to 70% by weight carbohydrates; and about 0.5 to 8% by weight of an emulsifier. The emulsifier may be a sugar ester, polyglycerol polyricinoleate, a polysorbate, a monoglyceride, or a mixture thereof. Preferably the emulsifier has a global hydrophilic lipophilic balance of  less than 5.
The coating composition may further include other ingredients such as sweeteners, flavorings, aroma agents, preservatives, colorants, or a mixture thereof. The other ingredients may be non-fat cocoa solids, coffee, caramel, and fruit.
The water phase of the coating composition may be a high water-containing food liquid or beverage. The high water-containing food liquid or beverage may be a fruit juice with pulp, a fruit juice without pulp, tea, coffee, honey, malt, caramel, maple syrup, or a mixture thereof.
The invention further relates to a method of preparing the coating composition. The coating composition is prepared by mixing water and the other ingredients at an acidic pH to prepare the aqueous phase; mixing a fat with an emulsifier at a temperature where the fat is liquid to prepare the fat phase; slowly introducing the aqueous phase into the fat phase while mixing to prepare a pre-emulsion; and further mixing the pre-emulsion under shear to form the emulsion, wherein the water phase represents about 80 to 65% by weight and the emulsifier represents about 0.5 to 8% by weight of the final composition. The method may also include pasteurizing the water phase in a high temperature short time mix plant having a high shear mix tank, heating/cooling exchanger, holding tubes and optionally a homogenizer.
The present invention also relates to a frozen confectionary product including a frozen dessert material and a coating composition in the form of a water-in-oil emulsion wherein the water-in-oil emulsion includes about 20 to 35% by weight fat phase; about 80 to 65% by weight water phase, wherein the water phase includes about 10 to 70% by weight carbohydrates; and about 0.5 to 8% by weight of an emulsifier. The coating composition may form a film, a layer, or an inclusion in the frozen dessert material.
The present invention also relates to a method of coating a piece of frozen dessert material by dipping the frozen dessert material in the water-in-oil coating composition, wherein the water-in-oil emulsion is at a temperature of about 28 to 40xc2x0 C.
The present invention also relates to a method of molding pieces of frozen confectionary by inserting the water-in-oil emulsion coating composition into a mold, removing excess coating composition to form a shell, filling in the shell with ice cream, backing off with additional liquid coating, inserting a stick, and demolding to remove the frozen confectionary from the mold. A frozen confectionary product may also be prepared by co-extruding the water-in-oil coating composition with ice cream from a die to form a coating, center, or ripple of the coating composition in the ice cream.
We have found that it is possible to produce a coating based on a water-in-oil emulsion which has texture and flavor properties that are superior to conventional fat-based coatings; significantly better keeping properties; better softness, e.g., less brittleness; and better adhesion to the frozen confectionary.
Accordingly, the present invention provides a water-in-oil emulsion for coating frozen dessert products, which comprises about 20 to 35% by weight of a fat phase; about 80 to 65% by weight of a water phase, wherein the water phase contains about 10 to 70% by weight carbohydrates; and the emulsion comprises about 0.5 to 8% by weight of an emulsifier system.
In the context of the invention the coating composition is not limited to surface coatings but also includes using the coating in applications where alternate layers of ice confectionary and coating are used to create layered products. The coating composition can also be used to form solid pieces which may be used, for instance, in place of chocolate inclusions.
The frozen dessert material may be any dairy or non-dairy product, for instance ice cream, iced milk, sherbet, sorbet, frozen custard, frozen yoghurt, or frozen mousse. It may be aerated or not aerated.
Advantageously, the emulsifier may comprise sugar esters, polyglycerol fatty acid esters, polyglycerol polyricinoleate (PGPR), polysorbates (polyoxyethylene sorbitan esters), monoglycerides, or combinations thereof, preferably with a global hydrophilic lipophilic balance (HLB) of  less than 5.
With respect to the water phase, high water-containing food liquids and beverages, such as fruit juice; with or without pulp; coffee; tea; honey; malt; caramel; or maple syrup may be used.
Sugar and other water-soluble compounds (e.g., humectants) preferably are present at levels exceeding about 5% by weight of the total coating composition and help to provide sufficient softening of texture and emulsion stability.
Other ingredients may be present including sweeteners, flavorings, or colorants, the proportions of which are determined according to taste and/or appearance. Non-fat cocoa solids, which may come from cocoa liquor or cocoa powder, may be used as flavorings. Other flavors, for example, coffee, may also be added, depending on preference.
With respect to the fat phase, fats such as coconut fat or vegetable fat stearin or blends with a liquid oil may be used, to give the required texture to the coating composition.
The water phase may contain a preservative, for example a sorbate or ascorbic acid, and preferably has a pH of about 2.5 to 5 in order to ensure that it will not support the growth of spoilage microorganisms.
Preferably the resulting water phase is pasteurized, for example, in a high temperature short time (HTST) mix plant consisting of a high shear mix tank, plate heating/cooling exchanger, holding tubes and optionally a homogenizer. As an alternative the heat exchanger may comprise a shell and a tube heating/cooling unit without a homogenizer.
The coating composition may further contain crispy inclusions, for example, cereals like expanded or toasted rice, or dried fruit pieces. These inclusions must be coated in moisture barriers to delay the absorption of moisture from the coating, which would eventually result in their becoming soggy.
The invention further relates to a method of preparing the previously defined coating composition. The method comprises mixing water, ingredients of the aqueous phase, preservatives, aroma agents, and sweetening agents at an acidic pH to make the aqueous phase, and separately mixing a fat phase with the emulsifier at a temperature where the fat is liquid. The aqueous phase is then slowly introduced into the fat phase while mixing to prepare a pre-emulsion, and then further mixing the pre-emulsion under shear depending on the composition of the emulsion and the thickness of the coating required. The water phase represents about 65 to 80% by weight and the emulsifier system about 0.5 to 8% by weight of the final composition.
The coating composition is prepared by dissolving the emulsifier in the molten fat at a temperature of about 25 to 50xc2x0 C. The aqueous phase is then separately warmed up to a temperature of about 30 to 45xc2x0 C. and progressively added to the fat phase under fine flow and agitation as a pre-emulsification step, thus forming a water-in-oil emulsion.
To achieve a desired viscosity for dipping application, the resulting water-in-oil emulsion is further sheared. This can be done in a batch with a U-shape stirring rod agitator at a higher speed, or in a colloidal mill; or continuously with a rotor/stator dispersing device or by pumping the pre-emulsion through a static mixer with a high flow speed. An in-line rotor/stator dispersing device and/or static mixer is preferred for a better consistency of the coating.
The final coating can be stored at a positive temperature, e.g., 20-22xc2x0 C., so that it is solidified. The coating can then be melted and mixed well for re-use.
A piece of frozen confectionary may be coated by the previously defined water-in-oil emulsion coating composition by dipping the piece into the coating wherein the coating composition is at a temperature of about 28 to 40xc2x0 C.
The products obtained with this method have very good resistance to melting at about 20xc2x0 C. compared to products dipped in water-based coatings. Water-based coatings containing a pure aqueous phase have a poor resistance to melting. In addition, water-based coatings need special equipment for subsequent cooling, sometimes to very low temperatures, to freeze the coating.
Resistance to melting was demonstrated with a drip test. The drip test was carried out with the following equipment: a stainless steel grid/sieve held on a support, a scale, and a computer connected to the scale to record weight at preset time intervals. The apparatus was placed in a room with controlled air temperature (20xc2x0 C.) and a relative humidity of about 50 to 60%. The drip test was performed according to the following procedure: a coated ice cream bar was weighed and placed on a grid/sieve of standard US 8 mesh with squared holes of 2.36 mm (0.0937 inch). The time was set to zero and the weight was recorded at pre-set time intervals with the computer. After 1 h, the test was stopped. Weights and the weight loss expressed per 100 g of initial weight were recorded. The test was conducted with the product of the present invention (prepared according to Example 1) and with a commercial product (SOLERO, as disclosed in EP-A-0710074) for comparison purpose. The results are given in following Table 1.
It is clear from the above results that the coating according to the present invention has a much better resistance to melting than known water-based coatings.
The coating composition may also be used to mold pieces of frozen confectionary. The molded pieces of frozen confectionary are prepared by inserting the liquid coating composition in a mold, removing excess liquid coating from the mold to form a shell, filling in the shell with ice cream, backing off with additional liquid coating, optionally inserting a stick, and demolding, e.g., by heating.
Ice cream pieces, portions, morsels, domes or cakes may also be coated using an enrober.
The invention also relates to the use of the coating composition to form a film, a layer or an inclusion in a frozen dessert.
In one embodiment, the coating composition is dropped onto a belt or band or into a mold followed by cooling to form solid pieces, e.g., drops of coating which can be used as inclusions in ice cream.
In another embodiment, the coating composition is sprayed to form a film or layer on the surface of an ice cream product, or films or layers inside an ice cream product to form a multilayered product.
In yet another embodiment, the liquid coating composition can be co-extruded with ice cream from a die to form a coating, a center, or ripple in the ice cream.